Fluid power control system for vehicles

ABSTRACT

A fluid power control system for a vehicle having forward, reverse and speed range clutches, and the vehicle being driven from a source of power, such as an internal combustion engine, through a torque converter, which is controlled by a fluid actuated and modulated main clutch. The control system includes inhibitor valve means which functions to inhibit the shifting of the clutches between forward and reverse directions above predetermined vehicle speeds, and also inhibit speed gear shifting in a downward direction above a predetermined speed. The control system also includes cross-over valve means connected with the direction clutches and the speed change clutches so that when a shift from one clutch to the other is called for by the action of the operator, the clutch which had been engaged is held in engagement until the newly selected clutch is at least partially engaged, and then the clutch which had been engaged is released. This functions to eliminate heat generation which is otherwise caused by slow shifting which in turn permits the vehicle power source to build up inertia energy in the power input parts, such as the flywheels, main clutch and torque converter. The cross-over valve means thus eliminates the heat build up due to the conventional between-gears-neutral position, and the valve means are effective regardless of how slowly the clutches are shifted.

United States Patent Hilpert 1451 Sept. 19, 1972 [54] FLUID POWER CONTROL SYSTEM [57] ABSTRACT FOR VEHICLES A fluid power control system for a vehicle having for- [72] Inventor: Conrad R. I-lilpert, Winnebago. lll. ward, reverse and speed range clutches. and the vehi- 61088 cle being driven from a source of power, such as an internal combustion engine, through a torque converter, [73] Asslgnee' Disc Incorporated Racine which is controlled by a fluid actuated and modulated main clutch. The control system includes inhibitor Filed; 1970 valve means which functions to inhibit the shifting of [211 App No: 66,182 the clutches between forward and reverse directions above predetermined vehicle speeds, and also inhibit speed gear shifting in a downward direction above a 1.8. C. C, R predetermined peed [5 1] Int. Cl. ..Fl6d 67/04, Fl6h 57/06 [58] w of surchmlgono R 77 R; 192/4 R, 4 A, The control system also 1ncludes cross-over valve 192/4 C means connected with the direction clutches and the speed change clutches so that when a shift from one [56] References cued clutch to the other is called for by the action of the operator, the clutch which had been engaged is held in UNITED STATES PATENTS engagement until the newly selected clutch is at least 3 458 0'8 7/1969 Show 192/4 C partially engaged, and then the clutch which had been 3348644 10/1967 Hiper't' "192/4 C engaged is released. This functions to eliminate heat 3400'60 9 I19 68 Rum C X generation which is otherwise caused by slow shifting 3'437l84 W969 Wilson 9214C which in turn permits the vehicle power source to 3481435 12/1969 Pearce "192/4 C build up inertia energy in the power input parts, such 3:540:556 11/1970 Snoy etal. .:.::::::::::l92/4C as flywhee's' main Primary Examiner-Kenneth H. Betts Assistant Examiner-Leslie J. Paperner Attorney-James F. Nilles The cross-over valve means thus eliminates the heat build up due to the conventional between-gearsneutral position, and the valve means are effective regardless of how slowly the clutches are shifted.

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FLUID POWER CONTROL SYSTEM FOR VEHICLES BACKGROUND OF THE INVENTION The invention pertains to fluid power control systems for vehicles, for example, those which operate in either direction, such as front end, earth moving loaders or the like. These control systems control the shifting of fluid clutches for changing the direction of travel of the vehicle as well as its speed in either direction. The transmissions used with such vehicles also include a torque converter which is driven from a power source through a modulatable and fluid actuated friction clutch. Considerable heat is generated in the clutches when shifting from one to the other is made at excessive vehicle speeds, and the control system of the present invention substantially eliminates this heat generating, as well as eliminating a second source of heat which is generated during the neutral gear position and which is due to the inertia of the moving parts of the transmission. This second source of heat in the clutches is caused by slow shifting of the clutches which permits the power source to store inertia energy in the input parts and permits the driven vehicle to be without driving torque and thereby slow down, thus increasing the heat dissipation for speed range to speed range shifts.

SUMMARY OF THE PRESENT INVENTION The present invention provides a fluid power control system for a vehicle which has brake, forward, reverse, and speed range clutches, and which vehicle is driven from a source of power, through a torque converter which in turn is controlled by a fluid actuated and modulated main friction clutch. The control system provided by the present invention includes inhibitor valve means which functions to inhibit the shifting of the clutches between forward and reverse directions and also inhibits speed gear shifting in a downward direction above a predetermined speed. The inhibitor valve means functions to actually apply the vehicle brakes when the operator has called for a reversal of vehicle direction or when the operator has called for a downshift of above a predetermined vehicle speed. In other words, the inhibitor valve means are effective when a call for reverse direction at excessive speeds is made and the modulated main clutch is disengaged, and the operator automatically applies the brake clutch.

The control system provided by the present invention also includes cross-over valves which are connected with the direction clutches and the speed change clutches so that when a shift from one clutch to another is to be made, the clutch which had been engaged is held in engagement until the newly selected clutch is commencing to be or is at least partially engaged, and then the clutch which has been engaged is released. The control system eliminates heat generation which is otherwise caused by slow shifting which in turn permits the vehicle power source to build up inertia energy in the power input parts, such as the flywheels, main clutch, and torque converter. The cross-over valves provided by the present invention eliminate the heat build up which is due to the conventional neutral position of the gears, and the cross-over valves are effective regardless of how slowly the clutches are shifted.

The present invention provides a fluid power control system for a vehicle which insures complete heat control of the clutches and torque safety of the transmission, combined with complete operator control and smooth shifting in either direction and at all speeds.

These and other objects of the present invention will appear hereinafter as this disclosure progresses, reference being had to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a fluid circuit diagram embodying the present invention and showing the inhibitor valve means as a box;

FIG. 2 is a more or less schematic diagram of the inhibitor valve means which is simply shown as a box in FIG. 1;

FIG. 3 is a fluid circuit diagram of one form of the fluid pressure supply circuit which is connected to the circuit of FIG. 1;

FIG. 4 is an enlarged view of the right hand portion of the FIG. I circuit, namely, the cross-over valve means;

FIG. 5 is an enlarged, more or less schematic view, of each of the foot pedal valves 35, 36 and 37 shown at the lower left end of the FIG. 1 circuit;

FIG. 6 is a schematic view of the foot control and hand shifting format for operating the various brake, forward and reverse foot operated valves, and the change speed gear valves;

FIG. 7 is a schematic view of a power transmission for a vehicle and with which the control system of the present invention is usable;

FIG. 8 is an enlarged, schematic cross sectional view of the main clutch control valve FIGS. 9 through 20 are diagrams showing the portions of the circuitry that are used for various shifting operations, as follows:

FIG. 9 is a circuit showing the power take off operation;

FIG. 10 is a circuit showing the low speed forward steady operation;

FIG. I I is a circuit showing the low speed forward at the time of a demand for backward motion;

FIG. 12 is a circuit showing the cross over terminat- FIG. 13 is a circuit showing the high speed forward steady;

FIG. I4 is a circuit showing the high speed forward and call for downshift;

FIG. 15 is a circuit showing the high speed forward call for backward;

FIG. 16 is a circuit showing the high speed call for brakes;

FIG. 17 is a circuit showing the medium speed called for downshift;

FIG. 18 is a circuit showing the cross over terminated;

FIG. 19 is a circuit showing the medium speed forward and call for backward; and

FIG. 20 is a circuit showing neutral.

DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention will be shown and described as applied to a power transmission for a vehicle V(FIG. 7), including a source of power such as an internal 

1. In a vehicle having ground engaging means, a power transmission and brake, forward and reverse clutches of the hydraulically actuated type for driving said means in forward and reverse directions and for stopping said vehicle, a pressure fluid circuit including manually operated brake, forward and reverse fluid control valves for said brake, forward and reverse clutches, respectively, said circuit also including a brake control fluid line, manually operated direction controls connected to said forward and reverse clutches for operation thereof, inhibitor valve means including shiftable element means in fluid communication with and for controlling flow of pressure fluid from said fluid control valves, fluid lines from said inhibitor valves to said forward and reverse fluid control valves, a fluid pump driven in proportion to the vehicle ground speed and in fluid communication with said shiftable element means to cause shifting thereof, whereby when said vehicle is moving above a predetermined speed in one direction and said pump is correspondingly pumping pressure fluid to said inhibitor valve means, then when one of said direction control valves is actuated by the operator in calling for a reversal of vehicle direction, said inhibitor valve means being in fluid communication with said reverse clutch and said manually operated brake will cause manually controlled pressure fluid to actuate said manually operated brake and prevent a reverse shift until said vehicle speed slows down below said predetermined speed, and then said inhibitor valve means will permit said reversal of direction.
 2. In a vehicle having ground engaging means, a power transmission and brake, forward and reverse clutches for driving said means in forward and reverse directions and for stopping said vehicle, and also having a first speed range clutch and a second speed range clutch for driving said vehicle at low and high speeds, said clutches being of the hydraulically actuated type, a pressure fluid circuit including manually operated brake, forward and reverse fluid control valves for said brake, forward and reverse clutches, respectively, a reverse inhibitor valve including a shiftable element in fluid communication with and for controlling flow of pressure fluid from said fluid control valves, a fluid pump driven in proportion to the vehicle ground speed and in fluid communicaTion with said reverse inhibitor valve shiftable element to cause shifting thereof, a downshift inhibitor valve including a shiftable element in fluid communication with and for controlling flow to said speed range clutches, said downshift inhibitor valve element also being in fluid communication with said pump and with said reverse inhibitor valve, whereby when said vehicle is moving above a predetermined speed in one direction and said pump is correspondingly pumping pressure fluid to said inhibitor valves, then (1) when one of said direction control valves is actuated by the operator in calling for a reversal of vehicle direction, said inhibitor valves will cause pressure fluid to actuate said brake clutch until said vehicle speed slows down below said predetermined speed, and then said inhibitor valves will permit said reversal of direction, and (2) when a downshift from said second speed range clutch to said first speed range clutch is called for by said operator, said inhibitor valves will cause pressure fluid to hold vehicle in its former gear until said vehicle slows down below a predetermined speed.
 3. In a vehicle having ground engaging means, a power transmission and brake, forward and reverse clutches of the hydraulically actuated type for driving said means in forward and reverse directions and for stopping said vehicle, a pressure fluid circuit including manually operated brake, forward and reverse fluid control valves for said brake, forward and reverse clutches, respectively, inhibitor valve means including a shiftable element means in fluid communication with and for controlling flow of pressure fluid from said fluid control valves, a fluid pump driven in proportion to the vehicle ground speed and in fluid communication with said shiftable element means to cause shifting thereof, whereby when said vehicle is moving above a predetermined speed in one direction and said pump is correspondingly pumping pressure fluid to said inhibitor valve means, then when one of said direction control valves is actuated by the operator in calling for a reversal of vehicle direction, said inhibitor valve means will cause pressure fluid to actuate said brake clutch until said vehicle speed slows down below said predetermined speed, and then said inhibitor valve means will permit said reversal of direction; said vehicle also having a pair of fluid actuated gear shift clutches, a fluid pressure operated shiftable control valve including a shiftable portion for each of said gear shift clutches, said shiftable control valves having an operatoring pilot at each end for shifting said portion, a high hold pressure line connected to each of said shiftable control valves and communicable with said portion, an apply pressure line connected to each shiftable control valve and communicable with said portion, a cross-over fluid circuit including a double check valve between the operating pilot of one of said shiftable control valves and an operator pilot of the other control valve, said cross-over fluid circuit also communicable with said shiftable portion, control means for applying fluid pressure from said apply pressure line to the pilot of one of said shiftable control valves via said cross-over fluid circuit while at the same time high hold pressure is applied to the other shiftable control valve to hold the latter and its associated clutch until the clutch of said one shiftable control valve commences to be engaged, and then the clutch of said other shiftable control valve is released.
 4. In a vehicle having ground engaging means, a power transmission and brake, forward and reverse clutches for driving said means in forward and reverse directions and for stopping said vehicle, and also having a first speed range clutch and a second speed range clutch for driving said vehicle at low and high speeds, said clutches being of hydraulically actuated type, a pressure fluid circuit including manually operated brake, forward and reverse fluid control valves for said brakE, forward and reverse clutches respectively, a reverse inhibitor valve including a shiftable element in fluid communication with and for controlling flow of pressure fluid from said fluid control valves, a fluid pump driven in proportion to the vehicle ground speed and in fluid communication with said reverse inhibitor valve shiftable element to cause shifting thereof, a downshift inhibitor valve including a shiftable element in fluid communication with and for controlling flow to said speed range clutches, said downshift inhibitor valve element also being in fluid communication with said pump and with said reverse inhibitor valve, whereby when said vehicle is moving above a predetermined speed in one direction and said pump is correspondingly pumping pressure fluid to said inhibitor valves, then (1) when one of said direction control valves is actuated by the operator in calling for a reversal of vehicle direction, said inhibitor valves will cause pressure fluid to actuate said brake clutch until said vehicle speed slows down below said predetermined speed, and then said inhibitor valves will permit said reversal of direction, and (2) when a downshift from said second speed range clutch to said first speed range clutch is called for by said operator, said inhibitor valves will cause pressure fluid to hold vehicle in its original gear until said vehicle speed slows down below a predetermined speed; said vehicle also having a pair of fluid actuated gear shift clutches, a fluid pressure operated shiftable control valve including a shiftable portion for each of said gear shift clutches, said shiftable control valves having an operator pilot at each end for shifting said portion, a high hold pressure line connected to each of said shiftable control valves and communicable with said portion, an apply pressure line connected to each shiftable control valve and communicable with said portion, a cross-over fluid circuit including a double check valve between the operating pilot of one of said shiftable control valves and an operating pilot of the other control valve, said cross-over fluid circuit also communicable with said shiftable portion, control means for applying fluid pressure from said apply pressure line to the pilot of one of said shiftable control valves via said cross-over fluid circuit while at the same time high hold pressure is applied to the other shiftable control valve to hold the latter and its associated clutch until the clutch of said one shiftable control valve commences to be engaged, and then the clutch of said other shiftable control valve is released. 